Huo Jingnan | WOSU Radio

Huo Jingnan

The nation's top coal mine safety regulator told members of Congress on Thursday that existing safety regulations are sufficient to protect miners from toxic dust, despite calls for change amid an epidemic of advanced black lung disease among coal miners in Appalachia.

Assistant Secretary of Labor David Zatezalo, testifying before the House Workforce Protections Subcommittee, said sampling from coal mines shows a 99% compliance rate with rules designed to limit workers' exposure to silica, the dust blamed for the disease outbreak.